1. Field of the Invention
This invention relates to a spacer and a parts attachment device for attaching a cathode ray tube (CRT) to a TV receiver cabinet while adjusting the spacing between the cabinet and the CRT without warping the cabinet.
2. Description of the Prior Art
FIG. 20 is a cross-sectional view of the parts of an example of a prior art CRT mounting structure. In FIG. 20, a boss 2 is integrally provided on the inside surface of a cabinet 1. Reference numeral 3 denotes a CRT, and numeral 4 denotes a CRT mounting flange provided on the side of the CRT 3. Located on the end of the boss 2 is a recess portion that holds a fixing screw 7 and a matching nut 5, with the nut 5 being held so that it cannot rotate. Numeral 6 denotes a fitting that is shaped like an inverted U, so it is open at the lower end. The inside of the top portion is indented to allow it to be bent down at each side, forming opposing flaps each having a cutout. The pair of cutouts is used to hold the boss 2 between the flaps.
The attachment of the CRT 3 to the cabinet 1 will now be described. First, the cabinet 1 is set level, the nut 5 is inserted into a hexagonal recess formed in the top of the boss 2, and the fitting 6 is placed over the boss 2. The CRT 3 is then positioned so that the flange 4 is on the fitting 6, and the fixing screw 7 is inserted into a hole in the fitting 6 through a hole in the flange 4 and screwed into engagement with the nut 5.
Screwing the fixing screw 7 into the nut 5 draws the nut 5 upward until it is in contact with the fitting 6, moving the fitting 6 to a position at which the gap between the cabinet 1 and the flange 4 is closed. Further tightening the fixing screw 7 deforms the top of the fitting 6 flat. moving the flaps of the fitting 6 towards each other, clamping the boss 2 between the flaps, to thereby affix the CRT 3 to the cabinet 1. This type of CRT mounting arrangement is disclosed by, for example, JP-A HEI 11-313276. Tightening the fixing screw 7 moves the fitting 6 into contact with the flange 4. Since the boss 2 is clamped between the opposing flaps of the fitting 6, the CRT 3 is attached to the cabinet 1 with an appropriate spacing being maintained between the cabinet 1 and the flange 4 that prevents the cabinet 1 being warped by the operation. However, a drawback of this configuration is that the CRT 3 is attached with a weak attaching force, which is the force by which the boss 2 is clamped by the opposing flaps of the fitting 6.
An object of this invention is to resolve the above-described weak attaching force that is a drawback of the prior art, by providing a spacer and a parts attachment device that enables parts to be securely affixed without warping the member to which the part is affixed.
To attain the above object, the present invention provides a spacer comprising a first cam having an inclined cam surface and a second cam having an inclined cam surface, with an overall length of the two cams being changed by contacting the cam surfaces together to move the cams relative to each other.
The above object is also attained by a device for attaching parts via a spacer comprising a first cam having an inclined cam surface and a second cam having an inclined cam surface, with an overall length of the two cams being changed by contacting the cam surfaces together to move the cams relative to each other.
The spacer can also include a ratchet means for preventing the overall length of the cams from decreasing. A configuration can be used in which the cams are cylindrical and the ratchet means comprises engaging teeth provided on the peripheral wall of one of the cams and a pawl provided on the peripheral wall of the other cam that engages with the engaging teeth of the first cam. Using cams that are cylindrical, the ratchet means can also comprise engaging teeth provided on the cam surface of one cam and a pawl provided on the cam surface of the other cam that engages with the engaging teeth of the first cam.
The spacer can also include a torque limiter provided on a threaded engaging portion of one cam that engages with a fixing screw, a torque of the screwing action of the fixing screw relative to the threaded engaging portion being larger than a ratchet torque of the ratchet means, so that when a cam is brought into abutment with a member by rotation of the fixing screw in the threaded engaging portion, the action of the torque limiter screws the fixing screw into the engaging portion.
The cams are moved relative to each other in a linear direction to change the overall length of the cams, and it is preferable to provide a means for coupling the two cams together, at least in their initial state.
As described in the above, in accordance with this invention, a spacer is constituted of the first and second cams, enabling the overall length of the spacer to be adjusted to match the gap between the CRT fixing flange and the cabinet. Enabling the flange to be directly attached to the cabinet by fixing screws resolves the problem of weak attaching force that is a drawback of the prior art mounting.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and following detailed description of the invention.